A wide assortment of rotary devices have been proposed for grating and dispensing measured amounts of hand soap and other fatty or waxy materials. For example, U.S. Pat. No. 969,204 (Shaver) discloses a soap dispensing machine having a cloverleaf shaped cutting blade axially mounted in an enclosure and coupled to a hand crank for rotating the blade while soap is pressed against its upper surface. U.S. Pat. No. 1,502,347 (Nelson) describes a soap dispenser having a rotating conical cutting surface with curved blades projecting upwardly from the inner surface of the cone, which is peripherally seated on an annular ridge and rotated by a hand cranked beveled gear mounted at its periphery. U.S. Pat. No. 673,662 (Schwechler) discloses yet another rotary design, in which a group of axially projecting serrated blades are mounted in a peripheral ring which is rotatably mounted at the output of a square, tubular enclosure.
While such devices have experienced varying degrees of commercial success, a common problem continues to be the tendency of existing grating devices to clog and/or stall, depending on the design of the cutting mechanism and the consistency of the material being grated. Clogging occurs when the material being grated builds up in the teeth or projections of the cutting blade, causing the blade to slide past the opposing block of material without cutting into it. Stalling occurs when the blade digs so deeply into the material that it becomes difficult or impossible to turn any further. In either event, the cutting effectiveness of the blade is reduced or rendered useless until it is cleared. Moreover, episodes of clogging or stalling generally increase the mechanical loading on the cutting mechanism, resulting in higher material and manufacturing costs for devices designed to handle these loads. Accordingly, there exists a need for a rotary grating device which minimizes or eliminates clogging and stalling, is strong enough to withstand regular use and yet is simple and inexpensive to manufacture.
It is therefore an object of the present invention to provide an improved rotary grating device which addresses these and other deficiencies in prior art designs.